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Hypericum perforatum
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===Flowering characteristics=== [[File:Hypericum perforatum 123.jpg|thumb|Blossom showing black colored dark glands at the edges of the petals]] The flowers are conspicuous and showy, measuring about {{convert|1.5|β|2.5|cm|abbr=on}} across, and are bright yellow with black dots along the edges of the petals.<ref name="Canada" /><ref>{{cite web |last1=Chen |first1=Shu-Yee |last2=Hamer |first2=Deborah |title=Common St.John's Wort |url=http://www.bio.brandeis.edu/fieldbio/EFG_DEB_SHU/species%20pages/St.John's%20Wort/St.John's%20Wort.html |website=A Field Guide to Non-Native Species of Eastern Massachusetts |publisher=Brandeis University |access-date=29 July 2023 |date=2003}}</ref><ref name="Stace">{{cite book|last=Stace|first=C. A.|author-link = Stace, C. A. |year=2010 |title=New Flora of the British Isles|url=https://archive.org/details/newflorabritishi00stac|url-access=limited|edition=Third|publisher=Cambridge University Press|location = Cambridge, U.K.| isbn=978-0-521-70772-5 |page=[https://archive.org/details/newflorabritishi00stac/page/n374 339]}}</ref> Each of the flowers normally has five large petals and five smaller leaf-like [[sepal]]s below them. The sepals are about {{convert|4|β|5|mm|abbr=on}} in length, green in color, are shaped like the head of a spear ([[Glossary of leaf morphology#lanceolate|lanceolate]] shape) with a pointed tip, and the same clear and black glands as the leaves. The petals are significantly longer, {{convert|8|β|12|mm|abbr=on}} in length, and have an oblong shape. They completely hide the sepals from the front side of the flower.<ref name="Jepson">{{cite web |title=''Hypericum perforatum'' subsp. ''perforatum'' |url=https://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=91766 |website=The Jepson Herbarium |publisher=University of California, Berkeley |access-date=29 July 2023 |date=2023}}</ref> The many bright yellow [[stamen]]s are united at the base into three bundles.<ref name="Jepson" /> The stalk portion of the stamens, the filaments, vary in length and stick out in every direction from the center of the flower.<ref name="Canada" /> The [[pollen]] grains are pale brown to orange in color.<ref>{{Cite web |title=Hypericum perforatum |url=https://pollenatlas.net/hypericaceae/hypericum/hypericum-perforatum |access-date=2023-09-27 |website=Pollen Atlas}}</ref> The flowers are arranged along one side of each flowering stem with two flowers at each node (a [[Inflorescence#Determinate or cymose|helicoid cyme]]) at the ends of the upper branches, between late spring and early to mid-summer.<ref name="Mehta">{{cite web |last=Mehta |first=Sweety |date=2012-12-18 |title=Pharmacognosy of St. John's Wort |url=http://pharmaxchange.info/press/2012/12/pharmacognosy-of-st-johns-wort/ |access-date=2014-02-16 |publisher=Pharmaxchange.info}}</ref> Each flowering stem bears many flowers, between 25 and 100, and also is quite leafy.<ref name="Jepson" /> The fruit of ''Hypericum perforatum'' is a capsule {{convert|7|β|8|mm|abbr=on}} in length containing the seeds in three valved chambers.<ref name="Jepson" /><ref name="Canada" /> Seeds that are separated from the capsules have a much higher [[germination]] rate due to an inhibiting factor in the capsule itself.<ref name="FSControl" /> The black and [[lustrous]] seeds are rough, netted with coarse grooves.<ref name=Manual>{{cite book |title=Gray's Manual of Botany |author= Merrit Lyndon Fernald |year= 1970 |editor= R. C. Rollins |publisher= D. Van Nostrand Company |edition= Eighth (Centennial) β Illustrated|isbn= 978-0-442-22250-5 |page= 1010}}</ref> Each seed is about {{convert|1|mm|abbr=on}} in size.<ref name="Jepson" /> Each plant may produce an average of 15,000 to 34,000 seeds.<ref name="FSControl" /> {{gallery|mode=packed |Hypericum perforatum sl4.jpg|Full plant |Hypericum perforatum plantlets.jpg|Seedlings |7=Hypericum-perforatum-frutos.jpg|8=Fruit|9=Hypericum perforatum HC1.JPG|10=Red staining liquid from a flower bud}}
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